ROYAL CITY, Wash. (AP) - A wildfire that burned an estimated 500 to 1,000 acres was threatening homes south of Royal City, about 50 miles northeast of Yakima, on Sunday, according to a television report.

Six agencies responded to the fire Sunday morning, and local crop dusters are providing air support, KHQ Television in Spokane reported.

The fire is burning in sage, grass and groundcover about six miles south of Royal City.

Firefighters began their attack late Sunday morning. There was no immediate word on how many homes were threatened or if any evacuations had been ordered.

The Northwest Interagency Coordination Center did not have any information about the fire. The state Department of Natural Resources referred calls to Grant County Fire District No. 10, but officials there could not immediately be reached Sunday afternoon.

The state's largest fires were in south-central Washington's Horse Heaven Hills, where nearly 90 square miles of grass, sagebrush and farm fields were burning in four separate fires sparked by lightning.

Only the McBee fire south of Benton City, where 50 homes were evacuated Friday, had been contained as of Sunday afternoon.